Purification and Characterization of a New L-Methioninase from Solid Cultures of Aspergillus flavipes

Ashraf S. A. El-Sayed 한국미생물학회 2011 The journal of microbiology Vol.49 No.1

L-Methioninase was purified to electrophoretic homogeneity from cultures of Aspergillus flavipes using anionexchange and gel filtration chromatography by 12.1 fold compared to the crude enzyme preparation. The purified enzyme had a molecular mass of 47 kDa under denaturing conditions and an isoelectric point of 5.8 with no structural glycosyl residues. The enzyme had optimum activity at pH 7.8 and pH stability from 6.8-8.0 at 35°C. The enzyme appeared to be catalytically stable below 40°C. The enzyme activity was strongly inhibited by DL-propargylglycine, hydroxylamine, PMSF, 2-mercaptoethanol, Hg^(2+), Cu^(2+), and Fe^(2+), with slight inhibition by Triton X-100. A. flavipes L-methioninase has a higher catalytic affinity towards L-methionine (Km, 6.5 mM and Kcat, 14.1 S^(-1)) followed by a relative demethiolating activity to L-homocysteine (Km, 12 mM and Kcat, 9.3 S^(-1)). The enzyme has two absorption maxima at 280 and 420 nm,typical of other PLP-enzymes. Apo-L-methioninase has the ability to reconstitute its structural catalytic state completely upon addition of 0.15 mM PLP. L-Methioninase has neither an appreciable effect on liver function, platelet aggregation, nor hemolysis of human blood. The purified L-methioninase from solid cultures of A. flavipes displayed unique biochemical and catalytic properties over the currently applied Pseudomonad enzyme.

Purification and Characterization of Anabaena flos-aquae Phenylalanine Ammonia-Lyase as a Novel Approach for Myristicin Biotransformation

Asmaa M. Arafa,Afaf E. Abdel-Ghany,Samih I. El-Dahmy,Sahar Abdelaziz,Yassin El-Ayouty,Ashraf S. A. El-Sayed 한국미생물·생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.4

Phenylalanine ammonia-lyase (PAL) catalyzes the reversible deamination of phenylalanine to cinnamic acid and ammonia. Algae have been considered as biofactories for PAL production, however, biochemical characterization of PAL and its potency for myristicin biotransformation into MMDA (3-methoxy-4, 5-methylenedioxyamphetamine) has not been studied yet. Thus, PAL from Anabaena flos-aquae and Spirulina platensis has been purified, comparatively characterized and its affinity to transform myristicin was assessed. The specific activity of purified PAL from S. platensis (73.9 μmol/mg/min) and A. flos-aquae (30.5 μmol/mg/min) was increased by about 2.9 and 2.4 folds by gel-filtration comparing to their corresponding crude enzymes. Under denaturing-PAGE, a single proteineous band with a molecular mass of 64 kDa appeared for A. flos-aquae and S. platensis PAL. The biochemical properties of the purified PAL from both algal isolates were determined comparatively. The optimum temperature of S. platensis and A. flos-aquae PAL for forward or reverse activity was reported at 30oC, while the optimum pH for PAL enzyme isolated from A. flos-aquae was 8.9 for forward and reverse activities, and S. platensis PAL had maximum activities at pH 8.9 and 8 for forward and reverse reactions, respectively. Luckily, the purified PALs have the affinity to hydroaminate the myristicin to MMDA successfully in one step. Furthermore, a successful method for synthesis of MMDA from myristicin in two steps was also established. Gas chromatography-mass spectrometry (GC-MS) analysis was conducted to track the product formation.

Biocidal Activity of Metal Nanoparticles Synthesized by Fusarium solani against Multidrug-Resistant Bacteria and Mycotoxigenic Fungi

Manal T. El Sayed,Ashraf S. A. El-Sayed 한국미생물·생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.2

Antibiotic resistance by pathogenic bacteria and fungi is one of the most serious global public health problems in the 21st century, directly affecting human health and lifestyle. Pseudomonas aeruginosa and Staphylococcus aureus with strong resistance to the common antibiotics have been isolated from Intensive Care Unit patients at Zagazig Hospital. Thus, in this study we assessed the biocidal activity of nanoparticles of silver, copper and zinc synthesized by Fusarium solani KJ 623702 against these multidrug resistant-bacteria. The synthesized Metal Nano-particles (MNPs) were characterized by UV-Vis spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and Zeta potential. The Fourier transform infrared spectroscopy (FTIR) result showed the presence of different functional groups such as carboxyl, amino and thiol, ester and peptide bonds in addition to glycosidic bonds that might stabilize the dispersity of MNPs from aggregation. The antimicrobial potential of MNPs by F. solani against the multidrug-resistant (MDR) P. aeruginosa and S. aureus in addition to the mycotoxigenic Aspergillus awamori, A. fumigatus and F. oxysporum was investigated, based on the visual growth by diameter of inhibition zone. Among the synthesized MNPs, the spherical AgNPs (13.70 nm) displayed significant effect against P. aeruginosa (Zone of Inhibition 22.4 mm and Minimum Inhibitory Concentration 21.33 μg/ml), while ZINC oxide Nano-Particles were the most effective against F. oxysporum (ZOI, 18.5 mm and MIC 24.7 μg/ml). Transmission Electron Microscope micrographs of AgNP-treated P. aeruginosa showed cracks and pits in the cell wall, with internalization of NPs. Production of pyocyanin pigment was significantly inhibited by AgNPs in a concentration-dependent manner, and at 5-20 μg of AgNPs/ml, the pigment production was reduced by about 15- 100%, respectively.

Textural Evaluation of Al–Si–Cu Alloy Processed by Route BC-ECAP

Esmaeil Damavandi,Salman Nourouzi,Sayed Mahmood Rabiee,Roohollah Jamaati,Jerzy A. Szpunar 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.8

In this study, route Bc of the equal channel angular pressing (ECAP) method has been successfully applied to the Al–Si–Cualloy at 400 °C. Scanning electron microscopy (SEM) and electron backscatter difraction (EBSD) were used to analyze themicrostructure. Texture evolution was studied by the X-ray difraction (XRD) technique. The microstructural results showedthat at least four passes of route BC need to access uniform distribution of fne intermetallic compounds (IMCs) and eutecticsilicon particles (ESPs). The particle stimulated nucleation (PSN) and continuous dynamic recrystallization (CDRX) aretwo important mechanisms to refne the aluminum matrix in Al–Si–Cu alloy. The texture results revealed that owing to achange in the rotation direction of route BC in consecutive passes, this process led to creating diferent types of textures, inboth qualitative and quantitative senses. The A*1Ѳ and A*2Ѳ were the strongest texture components after the fourth pass ofroute BC. Regardless of route A, the route BC-ECAP process led to strengthen the {100}⟨001⟩ and {011}⟨100⟩ componentsand weaken the {001}⟨310⟩ component. Three components, {100}⟨110⟩, {021}⟨501⟩, and {013}⟨313⟩ were developed byroute BC. The efects of route BC on texture homogeneity were also studied.

Heat transfer characteristics and entropy generation for wing-shaped-tubes with longitudinal external fins in cross-flow

Sayed Ahmed E. Sayed Ahmed,Osama M. Mesalhy,Mohamed A. Abdelatief 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.6

A numerical study is conducted to clarify heat transfer characteristics, effectiveness and entropy generation for a bundle of wingshaped-tubes attached to Longitudinal fins (LF) at downstream side. The air-side Re a ranged from 1.8 x 10 3 to 9.7 x 10 3 . The fin height (h f ) and fin thickness (δ) have been changed as: (2 mm ≤ h f ≤ 12 mm) and (1.5 mm ≤ δ ≤ 3.5 mm). The analysis of entropy generation is based on the principle of minimizing the rate of total entropy generation that includes the generation of entropy due to heat transfer and friction losses. The temperature field around the wing-shaped-tubes with (LF) is predicted using commercial CFD FLUENT 6.3.26 software package. Correlations of Nu a , St a , and Bejan number (Be), as well as the irreversibility distribution ratio (Φ) in terms of Re a and design parameters for the studied bundle are presented. Results indicated that, installing fins with heights from 2 to 12 mm results in an increase in Nu a from 11 to 36% comparing with that of wing-shaped tubes without fins (NOF). The highest and lowest values of effectiveness (ε) at every value of the considered Re a range are occurred at h f = 6 mm and (NOF), respectively. The wing-shaped-tubes heat exchanger with h f = 6 mm has the highest values of (ε), efficiency index (η) and area goodness factor (G a ) and also the lowest values of Φ and hence the best performance comparing with other arrangements. The minimum values of Φ are occurred at h f = 6 mm. (Be) decreases with increasing Re a for all studied h f . The heat transfer irreversibility predominates for (1800 ≤ Re a ≤ 4200) while the opposite is true for (6950 < Re a ≤ 9700). δ has negligible effect on Nu a and heat transfer irreversibility. Comparisons between the experimental and numerical results of the present study and those, previously, obtained for similar available studies showed good agreements.

EFFECT OF DROWSINESS ON DRIVING PERFORMANCE VARIABLES OF COMMERCIAL VEHICLE DRIVERS

A. MORTAZAVI,A. ESKANDARIAN,R. A. SAYED 한국자동차공학회 2009 International journal of automotive technology Vol.10 No.3

Driver drowsiness is a major safety concern, especially among commercial vehicle drivers, and is responsible for thousands of accidents and numerous fatalities every year. The design of a drowsiness detection system is based on identifying suitable driver-related and/or vehicle-related variables that are correlated to the driver’s level of drowsiness. Among different candidates, vehicle control variables seem to be more promising since they are unobtrusive, easy to implement, and cost effective. This paper focuses on in-depth analysis of different driver-vehicle control variables, e.g., steering angle, lane keeping, etc. that are correlated with the level of drowsiness. The goal is to find relationships and to characterize the effect of a driver’s drowsiness on measurable vehicle or driving variables and set up a framework for developing a drowsiness detection system. Several commercial drivers were tested in a simulated environment and different variables were recorded. This study shows that drowsiness has a major impact on lane keeping and steering control behavior. The correlation of the number and type of accidents with the level of drowsiness was also examined. Significant patterns in lateral position variations and steering corrections were observed, and two phases of drowsiness-related degradation in steering control were identified. The two steering degradation phases examined are suitable features for use in drowsiness detection systems. Driver drowsiness is a major safety concern, especially among commercial vehicle drivers, and is responsible for thousands of accidents and numerous fatalities every year. The design of a drowsiness detection system is based on identifying suitable driver-related and/or vehicle-related variables that are correlated to the driver’s level of drowsiness. Among different candidates, vehicle control variables seem to be more promising since they are unobtrusive, easy to implement, and cost effective. This paper focuses on in-depth analysis of different driver-vehicle control variables, e.g., steering angle, lane keeping, etc. that are correlated with the level of drowsiness. The goal is to find relationships and to characterize the effect of a driver’s drowsiness on measurable vehicle or driving variables and set up a framework for developing a drowsiness detection system. Several commercial drivers were tested in a simulated environment and different variables were recorded. This study shows that drowsiness has a major impact on lane keeping and steering control behavior. The correlation of the number and type of accidents with the level of drowsiness was also examined. Significant patterns in lateral position variations and steering corrections were observed, and two phases of drowsiness-related degradation in steering control were identified. The two steering degradation phases examined are suitable features for use in drowsiness detection systems.

Comparative Study of Itraconazole-Cyclodextrin Inclusion Complex and Its Commercial Product

Ibrahim A. Alsarra,Fars K. Alanazi,Sayed M. Ahmed,Ahmed A. Bosela,Suliman S. Alhamed,Hammam A. Mowafy,Steven H. Neau 대한약학회 2010 Archives of Pharmacal Research Vol.33 No.7

Itraconazole (ITZ) solid complex using hydroxypropyl-β-cyclodextrin (ITZ-HP-β-CD) with 20% polyvinylpyrrolidone was prepared by a co-evaporation method. The complex improved antifungal activity against C. parapasilosis and C. albicans. The complex demonstrated good flow and compressibility characteristics. The complex was formulated as a capsule dosage form and drug release was evaluated. Capsules containing ITZ-HP-β-CD at a molar ratio of 1:3 with 20% polyvinylpyrrolidone have a faster dissolution rate than commercial capsules (Sporanox ®). About 88% of ITZ was released in less than 30 min and the initial dissolution rate exhibited a 3.5-fold increase compared to the commercial product. UV spectrophotometeric, HPLC, and antimicrobial methods were used to determine ITZ concentration in the release medium and the results obtained by these methods are reported. It was found that HPLC analysis is a suitable and reliable method for determination of the drug concentration with a coefficient of variation less than 10%. The intraday precision showed a coefficient of variation less than 3.96%, and that for interday was less than 4.99%. The HPLC method was more accurate and precise than the antimicrobial and UV-spectrophotometric methods for determination of ITZ concentration present in the release medium.

Linear diarylheptanoids as potential anticancer therapeutics: synthesis, biological evaluation, and structure–activity relationship studies

A. F. M. Motiur Rahman,Yang Lu,이화종,조현지,Wencui Yin,Mohammad Sayed Alam,차효찬,Adnan A. Kadi,권영주,장영동 대한약학회 2018 Archives of Pharmacal Research Vol.41 No.12

In efforts to develop effective anticancer therapeutics with greater selectivity toward cancerous cell and reduced side-effects, such as emetic effects due to detrimental action of the drug toward the intestinal flora, a series of linear diarylheptanoids (LDHs) were designed and synthesized in 7 steps with good-to-moderate yields. All synthesized compounds were evaluated for their antibacterial, antiproliferative, and topoisomerase-I and -IIα inhibitory activity. Overall, all compounds showed little to no activity against the bacterial strains tested. Most of the synthesized compounds showed good antiproliferative activity against human breast cancer cell lines (T47D); specifically, the IC50 values of compounds 6a, 6d, 7j, and 7e were 0.09, 0.64, 0.67, and 0.99 μM, respectively. Among the tested compounds, 7b inhibited topo-I by 9.3% (camptothecin 68.8%), 7e and 7h inhibited topo-IIα by 38.4 and 47.4% (etoposide 76.9%), respectively, at the concentration of 100 μM. These results suggest that a set of promising anticancer agents can be obtained by reducing inhibitory actions on different microbes to provide enhanced selectivity against cancerous cells.

Seismic responses of base-isolated nuclear power plant structures considering spatially varying ground motions

Sayed, Mohamed A.,Go, Sunghyuk,Cho, Sung Gook,Kim, Dookie Techno-Press 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.54 No.1

This study presents the effects of the spatial variation of ground motions in a hard rock site on the seismic responses of a base-isolated nuclear power plant (BI-NPP). Three structural models were studied for the BI-NPP supported by different number of lead rubber bearing (LRB) base isolators with different base mat dimensions. The seismic responses of the BI-NPP were analyzed and investigated under the uniform and spatial varying excitation of El Centro ground motion. In addition, the rotational degrees of freedom (DOFs) of the base mat nodes were taken to consider the flexural behavior of the base mat on the seismic responses under both uniform and spatial varying excitation. Finally, the seismic response results for all the analysis cases of the BI-NPP were investigated in terms of the vibration periods and mode shapes, lateral displacements, and base shear forces. The analysis results indicate that: (1) considering the flexural behavior of the base mat has a negligible effect on the lateral displacements of base isolators regardless of the number of the isolators or the type of excitation used; (2) considering the spatial variation of ground motions has a substantial influence on the lateral displacements of base isolators and the NPP stick model; (3) the ground motion spatial variation effect is more prominent on lateral displacements than base shear forces, particularly with increasing numbers of base isolators and neglecting flexural behavior of the base mat.

A MIXED PROBLEM FOR A SECOND ORDER STURM-LIOUVILLE EQUATION

El-Sayed, A.M.A. Department of Mathematics 1992 Kyungpook mathematical journal Vol.32 No.2